Benchtop Thickness Planers

Benchtop Thickness Planers

A benchtop planer is ideal for professional or hobbyist woodworkers with limited shop space, or who don’t mill large quantities of lumber, and for contractors who want to be able to dimension stock on a job site. While they aren’t designed for heavy duty continuous use, they excel at producing precisely milled, smoothly finished stock very quickly. This article provides an overview of some of the important features to consider when purchasing your first, or a replacement, planer. For your convenience, we also have a comparison table that provides baseline specifications, and links, to 17 popular models.

Maximum Cutting Width and Depth

The maximum cutting width of a planer is determined by the size of its cutterhead, which is suspended below the motor and above the planer bed (or table). The knives that attach to the cutterhead are the same width as the cutterhead.

Planers come in 12″, 12-1/2″ and 13″ cutterhead widths. A decade or so ago you would be hard pressed to find a planer with a 13″ cutterhead. Today, they’re the most common size, and it wouldn’t come as a surprise if manufacturers dispense with narrower cutterheads as they bring new planer models to market. Wider, in this case, is better.

Maximum cutting depth is a non-issue, as all planers can mill stock up to 6″ thick (the Makita has a 6-3/32″ capacity). One less thing to clutter your mind with.

Depth of Cut

Manufacturers list the maximum amount of material that planers can remove in a single pass. They generally specify about 1/16″ for stock that is the full width of the cutterhead, and 1/8″ for narrower stock (typically around 6″ wide). The simple reason is that removing more stock would place too much strain on the rather small planer motor. When planing soft woods you can go by the manufacturers recommendations, but with hard woods, you’ll place less strain on the planer’s motor, and get a better finish, if you take shallow cuts – 1/32 to 1/16″. This isn’t a specification I would loose much sleep over.

Knives

There are two types of cutterheads. The conventional cutterhead uses a straight knife (or blade) – this is what you’ll find on the majority of planers. Cutterheads with 2 knives are most common, though three-knife cutterheads are becoming more widely available. Having three knives on the cutterhead should make the knives last longer between changes because there will be less wear on each knife for the same amount of work done. All manufacturers, by the way, use HSS (high speed steel) knives.

At one time manufacturers used thick (1/8″) resharpenable knives. Increasingly however, they are using disposable reversible knives. These thinner (1/16″) knives have a cutting edge on both sides, and when one side dulls you simply turn the knife around to expose the fresh cutting edge. My guess is that these are less expensive to manufacture. Regardless, when you factor in the cost of resharpening, reversible knives are price competitive. Remember that these disposable knives are recyclable.

Recently, Steel City and General have introduced planers with helical cutterheads, which use small square cutter knives arrayed in a spiral wrap around the cutterhead. The cutters on these planers are 2-sided – when a cutter becomes worn or is chipped, you rotate it to expose a fresh side. In busy shops this is a real benefit, as it reduces down time. The cutters are made of carbide steel, which hold an edge longer than HSS. Helical cutterheads also run quieter than conventional cutterheads and they produce less tear out on lumber with wild grain. As with conventional cutterheads, they do leave milling marks on stock that needs to be sanded or hand planed before a finish is applied.

Knife Changing

It used to be that changing knives was irksome and time consuming. No so today. Most manufacturers use self-indexing (quick change) knives. The knives have elongated holes that enable you to simply drop them onto registration pins on the cutterhead. A cutterhead with self-indexing knives is a thing of beauty.

Rotating or swapping out cutters on a helical cutterhead is very easy, though perhaps somewhat more time consuming, as there are 26 cutters to deal with.

The cutterhead has a tendency to move as you unscrew the knives. Some planers have a lock that keeps the cutterhead from moving. Not a deal breaker, but a nice feature to have.

Feed Rate

The feed rate is the speed, measured in feet per minute (FPM), that stock passes through the planer. The most common feed rate is 26 FPM. This is somewhat of a compromise rate that meets the needs of contractors and cabinet makers better than the needs of furniture makers. It’s a moderate feed speed that processes stock fairly quickly and delivers a reasonably good finish, quite suitable for stock that will be painted. If you work primarily with hard woods, especially those with interlock grain, a slower feed rate will give a better finish. Fortunately, there are a few planers that have dual feed rates – a low 14 to 18 FPM rate, and a faster (usually 26 FPM) rate.

Cuts Per Inch (CPI)

There is a specification that you’ll want to pay attention to. The CPI is affected by the feed rate (FPM), the number of knives on the cutterhead, and the motor speed (RPM). Rather than being overly concerned with these three individual factors, keep an eye on the CPI – the more cuts per inch, the better a finish you can expect. A 2-knife planer that cuts at 96 CPI will give a finish as clean as a 3-knife planer with the same CPI. The knives on the 3-knife planer will probably stay sharper a bit longer because each knife is doing less work.

Motor

All planers, save a lonely Craftsman, use 15-amp universal motors. They’re light, loud, inexpensive to manufacture, and they can run on a standard 110/120-Volt circuit. Excessive heat is the number one enemy of universal motors, so most are now equipped with thermal overload protection, which will automatically shut the motor down when it reaches a critical temperature – and before it overheats. This is a feature you don’t want to overlook. That’s really all you can tell about a planer motor, as manufacturers don’t necessarily provide NEMA (National Electrical Manufacturers Association) or IEC (International Electrotechnical Commission) ratings on their web sites. The ratings can be found on the motor nameplate (though the motor is often enclosed in a housing). For more information on motors read Siemens excellent primer.

Anti-Snipe Locks

Snipe is the shallow depression that occurs at the front or rear of a board after it passes through the planer. It can be caused by a board entering the cutterhead with the front or rear of the board elevated, or by vibration of the cutterhead assembly. Anti-snipe (or cutterhead) locks do help stabilize the cutterhead, though they don’t completely eliminate snipe, particularly on very long stock or thin stock. To increase stock support, some manufacturers include in-feed and out-feed tables.

Depth Stop

The depth stop (or depth lock) on a planer is very similar to that found on a plunge router. You can select, from a range of specific thicknesses, the depth below which you can’t lower the cutterhead. Not all planers offer this feature. Others provide three or four stops, while a few models provide a fairly wide range, from 1/8″ to 1-3/4″. For quickly processing lumber to specified thicknesses, a depth stop is a handy feature to have. However, you need to keep you planer clean, as dust and debris can clog up the mechanism. For precision work, it’s still a good idea to rely on calipers to confirm your final thickness.

Material Removal Gauge

The material removal gauge (or depth-of-cut indicator) lets you know how much material will be removed in a single pass through the planer. Most planers use an inverted pin that takes a measurement at a single spot. However, a pressure bar that runs the full width of the planer, on the infeed side, provides a more accurate indicator of the depth-of-cut. In any event, it’s a good idea to remove no more than 1/16″ to 1/32″ on each pass.

Thickness Scale

The thickness scale (or vertical depth scale) displays what will be the stock thickness after running through the planer. Some scales are difficult to read, and the graduations on the scale coarse. Don’t assume the scale is accurate – more than likely you’ll need to calibrate the scale when you first purchase the planer, and intermittently thereafter. You can also add a digital readout scale (see Planer Accessories).

Noise Level

Planers are among the worst noise polluters in a workshop, so hearing protection is vital – regardless of the planers rated decibel level. Sustained exposure to noise between 90 and 95 decibels can result in hearing loss, and noise levels from planers can be as high as 105 decibels. Planers with helical cutterheads are somewhat quieter, though hearing protection is still mandatory.

Extension Tables

To reduce snipe, it’s important that stock is fully supported before and after it passes under the cutterhead. Which is why most planers comes with both infeed and outfeed tables. Longer tables are always better. Ideally you want extension tables can be easily adjusted level with the planer table, and angled upwards or downwards at their ends. However, extension tables don’t, by themselves, eliminate snipe. For that, you’ll want to read our tips on Taming Snipe, below.

Dust Collection

Planers can generate huge amounts of sawdust, so being able to efficiently manage the waste is important. Oddly enough, a few models are not equipped with a dust port, or offer it as an optional add-on. The wood chips just spew out the outfeed side of the planer. This might be suitable if you mill very small quantities of wood, and don’t mind sweeping up after each use of the planer.

Other models do come with at least a 2-1/4″ or 2-1/2″ dust port, to which you can connect a shop vacuum. However, shop vacuums are not designed to handle the large volume of wood chips that planers generate – the small diameter hoses can quickly clog up, and the vacuum canister will fill up very quickly.

Planers that include a 4″ dust port enable you to connect to your shops dust collector. If you regularly mill lumber, this is by far the best way to manage planer waste.

Return Rollers

Stock return rollers are included on some planers. They can be in the form of steel rollers or aluminum rails, and are located on top of the planer.

They make it somewhat easier to transfer stock back to the infeed side of the planer. This is quite convenient if you’re milling a lot of stock.

Weight

Planers range in weight from about 50 to almost 100 pounds. The lighter models can probably be called portable. In most shops they are mounted on a wheeled table – so they can be moved around the shop or out of the way when not in use – or they are regulated to a stationary cart. Unless you regularly transport a planer to and from a job site, planer weight shouldn’t be much of a concern. In fact, a heavier planer will likely be subject to less vibration.

Warranty

As with any portable or stationary power tool, a longer warranty is preferable. Warranties range from 1 to 5 years. The price differential between a 1-year and 5-year warranty is pretty economic insurance, particularly if you use your planer on a daily basis. Note however, that most manufacturers don’t warranty these planes for commercial use.

Picking the Right Thickness Planer

The right planer for you will depend, among other things, on the kind of work you do and the budget you have available. The features that we feel are most important to look for include:

3-knife cutterhead (helical cutterhead for a full-time woodworker)

Self-indexing, reversible knives

High CPI (cuts per inch)

Anti-snipe lock

Wide range of depth stop settings

Wide extension tables that are easy to adjust

4″ dust port

Multi-year warranty

Taming Snipe

There are several ways you can minimize snipe.

Feed your stock through the thickness planer butt-end to butt-end. However, feed a sacrificial board (the same thickness as your stock) as the first board, and then again as the last board. Any snipe will occur on the sacrificial board. Remember to keep the stock butted together – if there is a gap between boards you run the risk of snipe.

Support long boards with roller stands on both the infeed and outfeed ends. This is particularly useful when milling long, heavy timbers.

Place thin stock (3/4″ or less) on a sub-base before feeding it through the planer. You can wedge thicker pieces in place, or use double sided tape to secure thin stock.

Install a long auxiliary bed through the mouth of the planer and over the infeed and outfeed tables. Go to our Planer Resources page for a link to Fine Woodworking magazine’s free ‘Shopmade Planer Table’ plan.

Planing Tips

Planers are quite safe, and easy to use. To get the best results, while maximizing your health and safety, follow these helpful planing tips.

Wear ear protectors, a respirator, and safety glasses.

Avoid planing stock less than 8″ long. Short pieces can get caught up between the cutterhead and pressure rollers.

If you plan on milling recycled lumber use a metal detector to check for metal objects.

Make sure that the planer’s extension tables are level and in line with the bed. Some people find that tilting the ends of the extension tables so that they are slightly above the level of the bed helps reduce snipe.

Take no more than 1⁄16″ to 1⁄32″ off your stock on each pass. This puts less strain on the planer motor, and helps reduce tearout.

Clean the planer bed frequently with a dry coat lubricant or wax, and clean the feed rollers whenever they begin to clog up with debris. This will help ensure your stock isn’t scratched by debris as it moves through the planer.

Replace the blades when you notice that your stock is no longer producing clean, flat surfaces.